Fuel cell system comprising battery and method of consuming residual fuel in the fuel cell system

Abstract

A fuel cell system having a back-up battery and a method of consuming residual fuel in the fuel cell system in which the fuel cell system includes a fuel cell, a system controller, a back-up battery, a converter, a fuel supply control, and a driver to drive the fuel supply control, and a charger disposed between the converter and a load. A power output end of the charger is directly connected to the back-up battery via a switch. The converter includes a first converter connected to the back-up battery and a second converter connected to the fuel cell, and the first and second converters are commonly connected to the charger.

1 . A fuel cell system, comprising:
 a fuel cell to supply energy to a load from a fuel;   a back-up battery to supply energy to the load and to store energy from the fuel cell;   a fuel supply control to control a flow of the fuel from a cartridge to the fuel cell;   a driver to drive the fuel supply control according to a control signal;   a charger disposed to charge the back-up battery through the consumption of residual fuel in the fuel cell;   a converter unit to convert power from the fuel cell and the back-up battery and to supply the converted power to the charger and the driver;   a first switch disposed between the charger and the load; and   a system controller to selectively charge the back-up battery and to selectively adjust the control signal to utilize a residual amount of fuel in the fuel cell when the first switch is open.   
   
   
       2 . The fuel cell system of  claim 1 , wherein an output of the charger is directly connected to an input of the back-up battery via a second switch. 
   
   
       3 . The fuel cell system of  claim 1 , wherein the converter unit comprises:
 a first converter having an input connected to the back-up battery; and   a second converter having an input connected to the fuel cell,   wherein outputs of the first and second converters are commonly connected to an input of the charger.   
   
   
       4 . The fuel cell system of  claim 3 , wherein a second switch is disposed between the back-up battery and the first converter, and a third switch is disposed between the output of the second converter and the charger. 
   
   
       5 . The fuel cell system of  claim 3 , wherein the first converter supplies power from the back-up battery to the driver, and the second converter converts a power output by the fuel cell to a power suitable for the load. 
   
   
       6 . A method of consuming residual fuel in a fuel cell system, the method comprising:
 comparing a first power and a second power, the first power being an output power from a fuel cell of the fuel cell system, and the second power being an intrinsic power consumed by the fuel cell system during operation;   driving the fuel cell system in a power loss mode if the first power is less than the second power, the power loss mode being an operation in which the first power is consumed by at least a converter unit and a charger of the fuel cell system;   determining whether a back-up battery of the fuel cell system is completely charged if the first power is greater than the second power;   driving the fuel cell system in a valve OFF driving mode if the back-up battery is determined to be completely charged and the first power is determined greater than the second power, the valve OFF driving mode being an operation in which the converter unit consumes power and an OFF signal is applied to a valve driver of the fuel cell system to consume power from the back-up battery, the valve driver controlling a valve which provides the fuel to the fuel cell;   driving the fuel cell system in a charge mode when the back-up battery is determined to be not completely charged and the first power is greater than the second power, the charge mode being an operation in which the back-up battery is charged to a full charge state;   comparing an output voltage from the fuel cell and a set voltage during one of the power loss mode, the charge mode, and the valve OFF driving mode; and   repeating the comparing of the first power with the second power, the driving the fuel cell system in the power loss mode, the determining whether the back-up battery is completely charged, driving the fuel cell system in the valve OFF driving mode, the driving the fuel cell system in the charge mode, and the comparing the output voltage from the fuel cell and the set voltage if the output voltage from the fuel cell is greater than the set voltage.   
   
   
       7 . The method of  claim 6 , wherein, the driving the fuel cell system in the charge mode comprises changing to the power loss mode if the output voltage from the fuel cell is greater than the set voltage and the first power is less than the second power. 
   
   
       8 . The method of  claim 6 , wherein, the driving the fuel cell system in the power loss mode comprises not supplying a fuel supply to the fuel cell, disabling a first converter of the converter unit, enabling a second converter of the converter unit and a charger, and a driver and the back-up battery are maintained in an inactive state. 
   
   
       9 . The method of  claim 6 , wherein, the driving the fuel cell system in the charge mode comprises not supplying a fuel supply to the fuel cell, a first converter of the converter unit and a driver are maintained in an inactive state, enabling a second converter of the converter unit and a charger, and electrically connecting a power output end of the charger and the back-up battery. 
   
   
       10 . The method of  claim 6 , wherein the driving the fuel cell system in the valve OFF driving mode and not supplying a fuel supply to the fuel cell comprises:
 enabling a first converter of the converter unit and a second converter of the converter unit;   maintaining the valve driver in an active state;   disabling the charger;   maintaining the back-up battery in an active state; and   applying an OFF driving signal to the valve driver.   
   
   
       11 . The method of  claim 10 , wherein the first converter is enabled before the second converter is enabled among the first and second converters. 
   
   
       12 . The method of  claim 10 , wherein the second converter is enabled before the first converter is enabled among the first and second converters. 
   
   
       13 . The method of  claim 10 , after applying the OFF driving signal to the driver, the method further comprising:
 driving the fuel cell system in the charge mode to charge the back-up battery;   determining whether the output power from the fuel cell reaches a set power; and   disabling the first and second converters and the charger if the output power from the fuel cell reaches the set power, and repeating the driving of the fuel cell system in the charge mode if the output power from the fuel cell does not reach the set power.   
   
   
       14 . The method of  claim 10 , after applying the OFF driving signal to the driver, the method further comprising:
 disabling the first converter;   determining whether the output power from the fuel cell reaches a set power; and   disabling the first and second converters and the charger if the output power from the fuel cell reaches the set power, and enabling the charger and electrically connecting a power output end of the charger and the back-up battery if the output power from the fuel cell does not reach the set power.   
   
   
       15 . The method of  claim 6 , wherein a fuel supply control comprises a valve disposed between a fuel cartridge and the fuel cell, and a driver comprises a valve driver. 
   
   
       16 . The method of  claim 6 , wherein a first switch is disposed between a back-up battery and a first converter and a second switch is disposed between the output end of the second converter and the charger. 
   
   
       17 . The method of  claim 6 , while driving the fuel cell system in a valve OFF driving mode, the method further comprising:
 enabling a second converter of the converter unit to supply the first power from the fuel cell to the charger;   determining whether the back-up battery is completely charged;   enabling the charger if the back-up battery is determined to be not completely charged so as to supply energy from the charger to the back-up battery;   if the back-up battery is determined to be completely charged, enabling a first converter of the converter unit to supply power to the charger, disabling the charger, applying the OFF control signal to the valve driver, and disabling the first converter; and   determining whether the first power has reached a set power.   
   
   
       18 . A computer readable medium comprising instructions that, when executed by a controller of a fuel cell system, cause the fuel cell system to perform the method of  claim 6 . 
   
   
       19 . The method of  claim 6 , wherein the driving the fuel cell system in a valve OFF driving mode further comprises:
 applying valve OFF signals to a valve driver if the back-up battery is completely charged to consume power from the back-up battery.   
   
   
       20 . The method of  claim 19 , wherein, after the power of the back-up battery is consumed by applying valve OFF signals to the valve driver, operating in the charge mode to re-charge the back-up battery. 
   
   
       21 . A method of consuming residual fuel in a fuel cell of a fuel cell system, the method comprising:
 after removing a load from the fuel cell system, determining whether a first power is less than a second power, the first power being a power output of the fuel cell, and the second power being a power required to operate the fuel cell system;   if the first power is less than the second power, operating the fuel cell system in a power loss mode to consume the residual fuel in the fuel cell;   if the first power is not less than the second power, determining if a back-up battery is completely charged;   if the back-up battery is completely charged and the first power is not less than the second power, operating the fuel cell system in a valve OFF driving mode to consume the residual fuel in the fuel cell by discharging the back-up battery through operation of a fuel cell element; and   if the back-up battery is not completely charged and the first power is not less than the second power, operating the fuel cell system in a charge mode to charge the back-up battery and consume the residual fuel in the fuel cell by charging the back-up battery.   
   
   
       22 . The method of  claim 21 , wherein power of the back-up battery is consumed by apply a valve OFF control signal to a valve driver if the first power is not less than the second power and the back-up battery is determined to be completely charged. 
   
   
       23 . A fuel cell system, comprising:
 a fuel cell to supply energy to a load from a fuel;   a back-up battery to supply energy to the load; and   a controller to control the fuel cell system to consume residual fuel in the fuel cell by alternately charging the back-up battery and consuming power of the back-up battery through the operation of the fuel cell system.   
   
   
       24 . A fuel cell system, comprising:
 a fuel cell to supply energy to a load from a fuel;   a back-up battery to supply energy to the load;   a charger disposed between the converter unit and the load to charge the back-up battery;   a valve driver to control a valve through which fuel enters the fuel cell;   a first switch disposed between the load and the charger;   a second switch disposed between the charger and the back-up battery; and   a controller to apply control signals to the charger and the valve driver to consume residual fuel in the fuel cell, after the load is removed from the fuel cell, so that a power of the back-up battery is consumed through the application of a valve OFF signal to the valve driver and the residual fuel is consumed in re-charging the back-up battery.   
   
   
       25 . The fuel cell system of  claim 23 , wherein the controller applies the control signal to consume the residual fuel in the fuel cell if the back-up battery is completely charged.